Producers, suppliers, and consumers of electrical power rely on energy meters to monitor power consumption and quality for numerous purposes, including billing and revenue, distribution, and process management. Traditionally, the primary means of measuring power consumption was an electro-mechanical power meter. A number of other types of meters and equipment measured other parameters of power generation, distribution, usage, and quality. As technology has improved, intelligent electronic devices (IEDs), such as digital power and energy meters, Programmable Logic Controllers (PLCs), electronically-controlled Remote Terminal Units (RTUs), protective relays, fault recorders, and the like, have slowly replaced their electro-mechanical and analog counterparts.
The shift to IEDs from analog and electro-mechanical devices provides a vast array of advantages including improvements in measurement accuracy (e.g., voltage, current, power consumption, power quality, etc.), system control (e.g., allowing a meter to trip a relay or a circuit breaker), and versatility (e.g., allowing a meter to share its data with another device). IED's typically implement system control and information sharing within in the analog signal realm. That is, a meter (or other IED) may provide an analog signal, such as a 0-1 mA signal, a 4-20 mA signal, a 0-5 V signal, or other analog signal, to another device. However, when an IED provides an analog output to share information with another device, or to control another device, the analog output frequently has a lower resolution than the data or control information conveyed by the analog signal. This deficiency is due, in part, to the cost of high-resolution digital-to-analog converters.